Pulse jet reaction motor having intermittent combustion



9, 1966 w. J. BOST 3,264,824

PULSE JET REACTION MOTOR HAVING INTERMITTENT COMBUSTION Filed Oct. 16, 194

8 Sheets-Sheet 1 INVENTOR.

Warm/L J. Bosi Mme/a Aug.'9, 1966 w. J. BOST 3,254,324

- PULSE JET REACTION MOTOR HAVING INTERMITTENT COMBUSTION Filed not, 16, 1964 INVENTOR.

Aug. 9, 1966 w. J. BOST 3,264,324

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United States Patent 0.

3,264,824 PULSE JET REACTION MOTOR HAVING INTERMITTENT COMBUSTION Warren J. Best, P.0. Box 661, Goldshoro, N.C. lFiled Oct. 16, 1964, Ser. No. 404,343 7 Claims. (Cl. 6039.78)

The present invention relates to an improved pulse jet reaction motor having resonant intermittent combustion means and, more particularly, the invention relates to a jet propulsion engine incorporating structural members including guide rods spaced from the combustion chamber that are generally parallel to each other for guiding the reciprocation of the chamber in cooperation with a dome-shaped member containing the ignition unit, for improving the utilization of the energy or force resulting from the explosive charge that is expelled from the combustion chamber and thus produce the jet action thereof.

The invention embodied in the structural members is such that combustion is begun at the outside limits of the due to the heat being generated therein, as well as'the overall surface area of the sphere being su'bstantially diminished, so that peripheral pressure thereby increases the explosive rate of the combustible material and consequently increases the forces generated. In the present invention, this principle is used in such a manner that a useful force is derived by enclosing the combustible on all sides except one, elongating the cylinder to a proportion that would provide the theoretical maximum force with a minimum of combustible expended, and then attaching a spring loaded closure. The invention seeks to provide an apparatus capable of developing almost full power at any altitude and under any conditions of rar-ification of the ambient material and limited conditions of compression.

One of the important features and advantages of the A further object of the present invention is to provide 7 means for initiating combustion'near the'rear end of the chamber. Q

It is a further object of the present invention to provide a jet propulsion engine incorporating structural members such as guide rods spaced apart from the combustion chamber that are parallel to each other for guiding the reciprocation of the chamber with respect to the door closure of the combustion chamber in cooperation with the dome shaped member containing the ignition unit in the combustion chamber. The propulsion unit of the invention embodies the concept of utilizing the energy or force of the explosive charge that is expelled from the combustion chamber to produce the jet action.

Another feature of the invention is to provide an electrical control and synchronizing system for actuating the ports or doors that open into and close the combustion chamber off from the outside. Also, the control system provides a cooling system to provide a sequence operation in controlling the temperature of the walls of the firing or combustion chamber. I e

'ice

Another feature of the present invention includes a combustion chamber in which a traveling wall of combustion gases is provided to travel from the rear portion of the combustion chamber toward the forward portion of the combustion chamber for compression of the residual gases that exist in the combustion chamber and thus provide an impetus in the force that is provided by the jet engine.

Another feature of the present invention is to provide a jet engine in which the combustion engine may slide along sets of parallel guide rods in which the port or door closure for the combustion chamber is stationary and securely mounted, while the combustion chamber may guide and slide along the guide rods. The invention is also provided with a spring for returningthe combustion chamber to its initial closed condition in engagement wit-h the closure.

Another feature of the invention is to provide spiral spring closure for returning the closure or gate to an initial position after the exhausted gases have been discharged from the combustion chamber. a r

A further feature of the invention is to provide a solenoid system for metering fuel to the combustion chamber and including asurge tank for providing positive displacements of the fuel gas or liquid by use of a double acting floating piston type dispensing valve.

A further feature of the invention is to provide a combustion chamber in which there is no port or closure plug member, but in which there is provided an ignition system in a combustion chamber in which a traveling wave .of combusted gases travels in a forward direction, along the side walls of the combustion chamber for compressing the gases that'existed within the chamber and discharge of the exhausted and heatedgases of the combustion chamber.

Another feature of the invention is to provide flame guides for effectively lengthening the firing chamber and giving additional thrust by containing the gases for a longer period of time prior to exhaustion thereof, and

.also to-direct the exhaustion along a generally linear path coaxial with the combustion chamber.

Another feature of the invention is to provide a re- .turnspringfor providing the return of the combustion chamber to an initial position after it has been displaced by the forward movement thereof due to the exhaustion and traveling wave of combustible gases and fuel that has been provided in the combustion chamber.

In accordance with a preferred embodiment of the present invention, upon ignition, the burning gases in the combustion chamber build up a flame barrier by means of internal pressures which begintoforce the firing chamber in a forward direction for compressing the return spring, and also the flame provides a traveling wave of 'combustedmaterial that compresses the air and gases in the forward end of the combustion chamber so that, as

the flame barrier containingthe unburned fuels within the firing chamber compresses the gases, the resultant implosion moves the firing chamber forward for compressing the return spring. At such point as the unburned fuel or burning fuel is dissipated so that the flame barrier breaks down, this break down allows exhausting of the burned and burning remains of the fuel around the exhaust plug for giving additional thrust.

One of the advantages of the invention is that the coolant is provided in the agent to keep the firing chamber within operating temperature ranges to extinguish any after-fire which would cause premature ignition of the following field charge as it is injected into the firing chamber and to block off any unburned fuel within the fuel injector tube.

Another feature of the invention is that the combustion chamber is provided with a door closure or exhaust plug for providing, among other things, a mount for the igniter, prestress of the return spring, block the exhaust end of the firing chamber to permit pressure build up of fuel for proper combustion, prevent the dissipation of unburned fuel, assist in guiding the escaping exhaust gases while providing the least amount of impedance to the exhaustion of gases, and provide stop guides for the exhaust ends of the firing cylinder.

These as well as further and other advantages which are enhanced in the invention will become apparent from the following description, reference being had to the accompanying drawing, wherein:

FIGURE 1 is a side elevational view, partially shown in cross-section, of a preferred embodiment of the present invention,

FIGURE 2 is a cross-sectional view taken along lines 2-2 of FIGURE 1 and showing the component parts of the invention,

FIGURE 3 is a similar cross-sectional view as FIG- URE 2, but showing the spring in substantial compression and the door closure in open relation with respect to the combustion chamber, in accordance with the operation of the invention,

FIGURE 4 is a cross-sectional view taken along line 4-4 of FIGURE 1,

FIGURE 5 is a cross-sectional view taken along line 5-5 of FIGURE 1,

FIGURE 6 is a cross-sectional view taken along line 6--6 of FIGURE 1,

FIGURES 7 and 8 show cross-sectional view of the jet engine of a modified arrangement in which FIGURE 7 shows the gases being exhausted from the combustion while FIGURE 8 shows the combustion chamber in its closed position,

FIGURE 9 shows a jet engine system according to the present invention in a cross-sectional view in which there is no plug for the combustion or firing chamber, within a modified embodiment of the present invention,

FIGURES 10, 11 and 12 show further embodiments of the present invention including certain details of the construction of the combustion chamber together with gates or ports for the accommodation of the injector tubes.

FIGURES l3 and 14 show a cross-sectional side view and an end elevational view, respectively, of a form of the invention embodying gates,

FIGURE 15 shows a spiral spring for providing closure means to the gates,

FIGURE 16 shows a check valve system for providing fuel, nitrogen or water, and oxygen, respectively, for injecting the charge to be ignited and also for killing the flame and providing cooling thereof, in accordance with the operation of an embodiment of the invention,

FIGURE 17 shows an end elevational view taken along line 1717 of FIGURE 16,

FIGURE 18 shows a fuel system of the present invention in elevational view, a part of which is broken away and a further part being shown in cross-section in which a nozzle orifice is used at the terminal end of the firing chamber in the absence of a gate or closure,

FIGURES 19 and 20 show a fuel metering system that may be used in conjunction with the present invention, and

FIGURE 21 shows a synchronizing and control system for use with the firing or combustion chamber of the jet pulse engine of the present invention.

Referring now to the drawings, there is shown a firing or combustion chamber which comprises a cylindrical tube of substantially constant diameter throughout the length thereof and having at the forward and closed end thereof a domed portion 12, and in which the 4 rear portion of the combustion chamber is opened at an orifice 14 as is shown in FIGURE 3.

Attached to the peripheral portions about the combustion chamber 10 are guide rod holders 18, as shown in FIGURE 2, set opposite and equidistant from each other. The combustion chamber is mounted between the rods 20 and is slidably mounted thereupon, in that the guide rods pass through the guide rod holders. The ends of the guide rods are bolted to a base plate 22, and the guide rods are constructed of solid metal. The other ends of the guide rods terminate and are bolted to an exhaust plug, gauge or door closure 24 mounted in the rear. The firing or combustion chamber 10 is seen to move forwardly and rearwardly along a parallel path formed by the guide rods as the guide holders move along the rods.

FIGURES 1, 2, 3 and 6 show a flame guide for aiding the exhaustion of spent gases while guiding and containing these gases as the firing or combustion chamber 10 moves forwardly along the guide rods. The flame guide, shown as element 26, is generally cylindrical and open at both ends, having a diameter slightly larger than that of the firing chamber 10. The flame guide is securely mounted upon the guide rods 20, 20 by a mounting ring 28 at or near the forward end of the flame guide 26. In addition to guiding the exhaust, the flame guide 26 is seen to effectively lengthen the firing chamber and provide additional thrust by containing the gases to pass along a coaxial path with the combustion chamber for a longer period of time prior to exhaust therefrom.

There is shown in FIGURES 1, 2 and 3, among others, a return spring 30 which is essentially a helical coil compression spring with reduced diameter end coil and is secured to the base plate 22. The other end of the return spring is secured to the dome portion 12 of the combustion chamber. A fuel injection line 32 passes through the base plate 22 in which there is a centered hole or opening 34 therein of sufficient diameter to permit the passage of the fuel line 32. The fuel injection line 32 is welded to the base plate at the opening 34, and as the combustion chamber 10 advances along its path, as shown in FIGURE 3, the injection line 32 advances along the combustion chamber as shown. The spring end guide is also welded to the base plate encircling the fuel injector line 32. The same arrangement for the spring end guide and opening for the fuel injector line is made in the domed portion 12 of the firing chamber, except that the firing chamber is free to travel along the fuel injector line, so that it advances therein. The exhaust plug or closure 24 is positioned on the guide rods 20, 20, to exert a predetermined pressure on the return spring 30 through the firing or combustion chamber 10 which butts against stops 36 located on the exhaust closure 34.

The size and strength of the return spring 30 is sufficient to overcome a force exerted upon the spring during combustion and the exhaustion thereof so that it readily travels the path shown from that position shown in FIGURE 2 to that shown in FIGURE 3, and returns. However, at no time is the force in the combustion chamber and the reaction, due to the exhaustion of the gases from the combustion chamber, suflicient to entirely compress the spring at the time of ignition and the for ward travel. As the firing or combustion chamber moves forward, the spring is compressed until the energy of the moving combustion chamber is dissipated. The spring then expands and returns the combustion chamber back to the guide stops 36 on the exhaust closure 24.

The advantages and operation of the return spring are made and designed so that it acts as a shock absorber, it smooths the shock of implosion spreading the force a longer period of time after combustion, it returns the firing chamber to the position for another fuel injection operation and it provides for closua'e of the combustion chamber with the guide stops 3 6. With the combustion chamber in its rearward position against the guide stops 36 on the exhaust closure, liquid or gaseous fuel together with an oxidizer are brought into the firing chamber to a system of concentric tubes 40 as shown in FIGURE 16. This system of tubes includes a line 42 for supplying fuel through a check valve 44, a line 46 for supplying nitrogen or water to a check valve 48 so that the system may be cooled and also for killing the flame in case where such is desired, and a line 50 is provided for supplying oxygen or sufficient air to aid the combustion operation after the fuel and the air mix in an injection nozzle 54, an end view of which is shown in FIGURE 17. The nozzle is always within the combustion chamber as it moves along its path. This fuel mixture with the air proceeds to the rear of the firing chamber 10 at which point it is ignited electrically by an igniter 60 mounted in the exhaust plug 24.

Upon ignition of the fuel mixture with the oxygen and air, the fuel provides burning gases which build up a flame barrier or wall by means of the internal pressures of the flame and the flame barrier or wall travels from the point of ignition along the length of the combustion so that the flame barrier or wall tends to compress and force the air in the firing chamber forward. This force also provides some measure of force upon the forward domed portion 12 of the combustion chamber so that the combustion chamber commences to compress the spring 30. The flame .barrier or wall within the combustion chamber contains the unburned fuels within the firing chamber, the resultant implosion moves the firing chamber further forward and further compressing the return spring. At this point, as the unburned fuel or burning fuel is dissipated so that the flame barrier breaks down, the breakdown of the flame barrier or wall allows exhaustion of the burned and burning remains of the fuel to be removed from the combustion chamber through the opening about the exhaust plug, the opening being formed by the displacement of the combustion chamber from the exhaust plug. This exhaustion provides a further thrust and moving force through the combustion chamber.

The injection of a coolant through line 46 is shown in FIGURE 16, and the cooling system is provided so that it is mounted within the oxidizing injection tube connected to line 50. FIGURE 21 shows a pressure switch 62 for controlling the injection of coolant in line 46, so that the force of the implosion increases the pressure within the oxidize-r injection tube and this activates the coolant injection valve 53 shown in FIGURE 21. The electrical system of FIGURE 21 also operates the coolant metering and injection system 53, 62, 64, so that the coolant is injected while the firing chamber is still in the forward position, such as shown in FIGURE 3. It is found that the coolant provides the advantages of keeping the firing chamber within operating temperatures, extinguishing any after-fire which would cause premature ignition of the following fuel charge in the firing chamber, and blocking off any unburned fuel with the fuel injector tube. The exhaust or closure 24 is a short, hollow, and cylindrically shaped domed element having at one end a constant diameter, slightly smaller than the internal diameter at the other end thereof. The smaller diameter is to provide a metered leak or leakage path about and around the exhaust plug 24 to allow the fuel charge to travel quickly from the end of the injection nozzle to the rear of the firing chamber and clearing the coolant from the firing chamber after its injection and placing the new fuel close to the igniter for the new cycle. In the top of the dome of the exhaust plug there is a hole or opening which is threaded to receive a spark plug -or igniter device 60.

The thrust developed by the imploding gases in the combustion chamber is proportional to the pressure under which the fuel is injected into the firing chamber. T 0

permit minimal thrust ranges, it is found essential to inject the fuel at minimal pressures. Such minimal pressure is insufficient, in the absence of a metered leak around the exhaust plug, to push the fuel to the point of ignition and clear the coolant without slowing the cycling of the engine.

There are several functions that are important in the use of the exhaust plug. These functions are that it provides a mount for the igniter, prestresses the return spring, blocks the exhaust end of the firing chamber to permit pressure build up of fuel for proper combustion, prevents the dissipation of unburned fuel, particularly at higher altitudes, shapes and guides the escaping exhaust gases while providing the least amount of resistance to the exhausting and provides stop guides for the exhaust end of the firing cylinder.

Where there is more than one combustion chamber in a system of engines for a craft there is a fuel, oxidizer and coolant metering system for each of the combustion chambers, and there is a coolant metering system for each of the fuel, oxidizer and coolant systems.

The system for providing and metering the fuel, oxidizer and coolant, consists of a high pressure or liquid gas tank 78, shown in FIGURES 19 and 20, a pressure regulating valve 79, and a stop valve connected between the high pressure tank and a surge tank 82. A stop valve 84 and an electrically operated solenoid valve 94 are mounted between the surge tank and the inner side of a metering tank 86, a tube connection 88 being provided between the outlet side of the metering tank through an electrically operated solenoid valve 96 and the injection tube 90. A high pressure cut-off switch 98, shown in FIGURE 21, is mounted within the metering tank to operate the inlet solenoid switch 94 at a predetermined variable pressure, and a low pressure cut-off switch 92 is mounted within the metering tank also to operate an outlet solenoid valve 96 at a predetermined constant pressure.

The gaseous fuel, oxidizer and coolant leave the high pressure tank through the pressure regulator into the surge tank 82. Upon opening of the inlet solenoid valve 94, the fuel moves from the surge tank under its own pressure into the metering tank '86. When the fuel in the metering tank reaches a predetermined variable pressure, which is varied in proportion to the amount of fuel desired, the high pressure cut-off switch 98 closes the inlet valve. The same high pressure cut-off switch operating the inlet valve also causes the synchronizing system to open the outlet solenoid valve 96. The fuel is then injected in through the firing or combustion chambers through the injector system and, as the pressure within the metering tank 86 drops in value, the low pressure cut-off switch 92 cuts off the outlet valve 96. The differential pressure between the high pressure cut-off switch and the low pressure cut-off switch determines the amount of fuel injected into the firing chamber 10. At the time of cutting off the outlet valve from the metering tank 86, the low pressure cut-off switch 92, acting through the synchronizing device 102, activates the igniter. The igniter causes the fuel charge to combust in the firing chamber 10. Shortly after ignition, the pressure switch 62 located in the oxidizer tube 50, as shown in FIGURE 16, activates the outlet solenoid 64 of the coolant injector against the injection of the coolant, as is described above.

The high pressure switch mounted within the metering tank is variable through a linkage through a manual control operated by the pilot of the aircraft, or a remote control system may be used to provide variability by a linkage that may be either the electrical or mechanical auxiliary control arrangement to vary fuel charged to offset the ambient pressure change or to vary the desired thrust and control of fuel and other parameters through the engine. The low pressure switch mounted within the metering tank is kept at a constant pressure that will insure quick injection of the fuel from the metering tank into the firing chamber. The faster the fuel can be injected into the combustion chamber 10, the increased number of cycles are achieved within a given time.

The control systems shown in FIGURES 16, 17, 18, 19, 20 and 21 show alternate types of fuel injection methods used to inject gases and liquids into the combustion chamber. It is recommended that use of gaseous fuels, oxidizer injection and coolant injection be made for two reasons, principally to avoid mechanical pumping and to avoid air lock in any atmospheric conditions or gravitational conditions.

The synchronizing device of FIGURE 21 is used to meter the fuel, oxidizer gas and coolant fluid, to open and close injection valves in prepared sequence, and to ignite the fuel charge in the firing chamber. The ignition system consists of motor driven breaker points 108, ignition coil 110, and igniter 60. The power supply is derived from a source of DC current, shown as a battery 114. The synchronizing system consists essentially of a motor drive cycling switch or driven breaker points 108 variable in speed from zero to a speed that will represent a maximum possible cycling of the engine with electrically operated magnetic switches 102 and pressure operated switches 92, 98, wired and connected for the proper sequence of injection and operation of the combustion chamber. The motor 118 is used to drive the breaker points 108, and the motor may also be useful in driving or operating other features of the system.

In FIGURE 18 there is shown a modified arrangement of a combustion chamber 10A in which there is no plug at the opening end thereof, but the necessary impedance to the outgo or outflow of gases is provided by the nozzle 122. The operation of the nozzle arrangement is well known in the art, and it is to be understood that the combustion chamber 10A may be correspondingly mounted upon the guide rods as shown in the principal embodiment of the invention.

FIGURES 7, 8 and 9 show a modified arrangement that contemplates the igniter device 60A to be mounted on the side of the combustion chamber adjacent to the plug 24A, but the igniter is mounted on the wall of the combustion chamber 10A. Also shown in FIGURES 7 and 8 is the concept that the injection tube or fuel injector 32A is projecting through the stern opening in the plug 24A and the plug is adapted to move along the course of travel due to the forces in the combustion chamber as opposed to the forces provided by the spring 30A. The embodiment of the invention in FIGURE 9 shows that the igniter 60B is mounted in a side wall of the combustion chamber 10B, and that the fuel, oxidizer fuel and coolant fluid are provided through the systems of lines or tubes 42, 46, 50, respectively.

An important modification to the invention includes the disposition of gate elements 132, 132, 132, as shown in FIGURES l3 and 14 for providing quick opening and closing apertures in or operated by the spiral spring means 136 which includes the spring 138 as shown in FIGURE 15. In this way the exhaustion of the combustion chamber is rapidly and eificiently accomplished, as well as the gate 132, 132, providing a director force to the exhausting gases in providing a curl to the flow of exhaust gases therefrom. The gate systems are further shown in the embodiment of FIGURES 10, 11 and 12 in which the injection tube 32C, 32D, 32E, are variously disposed in and about the combustion chamber for providing the control effects in the combustion of the fuel and gases applied therethrough. In these figures the combustion chamber is shown as 10C, 10D, 10E respectively, and are provided with the mounting as shown in the other embodiments of the invention. These figures also show the igniters 60C, 60D, 60E, respectively.

Additional embodiments of the invention in this specification will occur to others and therefore it is intended that the scope of the invention be limited only by the appended claims and by the embodiments described hereinabove. Accordingly, reference should be made to the following claims in determining the full scope of the invention.

What is claimed is:

1. A pulse jet engine comprising an elongated combustion chamber having its forward end closed and terminating in a domed shape cap, the rear end of the combustion chamber having a spring loaded closure for such chamber, igniting means mounted in said chamber proximate the rear end thereof, said igniting means initiating combustion near the rear end of said chamber and having a traveling wall of combustion proceeding along the length of the combustion chamber in a forward direction, said wall for compressing and increasing the pressure and the gases in the forward end of the combustion chamber, said combustion chamber being sufficient in length to cause a low pressure swell in pressure of the combustion chamber to cause the spring loaded closure to close and restart the cycle as long as the combustion chamber is fed with combustible material, at least two guide rods each attached at one end to said closure member, a pair of spaced rod holders slidably receiving each rod and mounted in longitudinally spaced relation on said combustion chamber for guiding said closure member in a reciprocating path to open and close said combustion chamber.

2. The invention according to claim 1 wherein a flame guide means is provided along the peripheral portion of the rear end of the combustion chamber to force the gases to be expelled from the combustion chamber in substantially a straight line rearwardly wherein the pulse jet engine is provided with substantially the maximum amount of reaction force.

3. The invention according to claim 2 wherein the flame guide means is mounted upon the peripheral portion of the combustion chamber.

4. The invention according to claim 3 wherein means are provided for metering fuels to the combustion chamber in measured quantities.

5. The invention according to claim 2 wherein circuit control means are provided for controlling and synchronizing the ignition circuit of the combustion chamber.

6. The invention according to claim 2 wherein pressure sensitive means are mounted at the forward end of the combustion chamber for controlling cooling means to protect the temperature of the elongated combustion chamber about its peripheral portions thereof.

7. The invention according to claim 2 wherein guide rods are provided for allowing the closure to reciprocate in opening and closing the combustion chamber.

References Cited by the Examiner UNITED STATES PATENTS 1,051,363 1/1913 Anderson 60-398 X 1,598,476 8/1926 Cribier. 2,924,071 2/1960 Paravicini 60-3977 MARK NEWMAN, Primary Examiner.

RALPH D. BLAKESLEE, Examiner. 

1. A PULSE JET ENGINE COMPRISING AN ELONGATED COMBUSTION CHAMBER HAVING ITS FORWARD END CLOSED AND TERMINATING IN A DOMED SHAPED CAP, THE REAR END OF THE COMBUSTION CHAMBER HAVING A SPRING LOADED CLOSURE FOR SUCH CHAMBER, IGNITING MEANS MOUNTED IN SAID CHAMBER PROXIMATE THE REAR END THEREOF, SAID IGNITING MEANS INITIATING COMBUSTION NEAR THE REAR END OF SAID CHAMBER AND HAVING A TRAVELING WALL OF COMBUSTION PROCEEDING ALONG THE LENGTH OF THE COMBUSTION CHAMBER IN A FORWARD DIRECTION, SAID WALL FOR COMPRESSING AND INCREASING THE PRESSURE AND THE GASES IN THE FORWARD END OF THE COMBUSTION CHAMBER, SAID COMBUSTION CHAMBER BEING SUFFICIENT IN LENGTH TO CAUSE A LOW PRESSURE SWELL IN PRESURE OF THE COMBUSTION CHAMBER TO CAUSE THE SPRING LOADED CLOSURE TO CLOSE AND RESTART THE CYCLE AS LONG AS THE COMBUSTION CHAMBER IS FED WITH COMBUSTIBLE MATERIAL, AT LEAST TWO GUIDE RODS EACH ATTACHED AT ONE END TO SAID CLOSURE MEMBER, A PAIR OF SPACED ROD HOLDERS SLIDABLY RECEIVING EACH ROD AND MOUNTED IN LONGITUDINALLY SPACED RELATION ON SAID COMBUSTION CHAMBER FOR GUIDING SAID CLOSURE MEMBER IN A RECIPROCATING PATH TO OPEN AND CLOSE SAID COMBUSTION CHAMBER. 